In the original conventional technology of fasteners employed to securely attach one object to another, such as for example one part to another in the case of an automobile or an appliance, has utilized a nut on one of the two objects, usually welded or glued to the back of said object, and a bolt passing through a hole on the second object in a manner to be engaged by the nut, thereby securing the two objects together.
This arrangement presents many problems, among which, one of the most important is that in the case that one object is hollow, the nut has to be in place at the back of the hollow object before assembling the two objects together. If for any reason the nut is misplaced, and/or if it becomes desirable to introduce a new fastening connection between the two objects, the task of achieving such connection becomes very difficult, if not impossible, for all practical purposes.
The so-called “quick nuts” have also been used to connect two objects. In addition, vibration during the operation of a device, such as an automobile or appliance for example, containing the two objects results very often in loosening of the bolt or “quick nut” and in either full disassembling of the objects from each other, or in a vibration noise which is most annoying and often of unacceptable levels. Further, such connections are not water-resistant and water may be easily penetrate the connection point and be transferred from one side of one or both objects to the other side.
Fasteners of the type described in U.S. Pat. No. 4,500,238 (Vassiliou) have been utilized to reduce considerably the potential of bolt or screw loosening and vibration. They have also eliminated the problem of having to place one member of the fastener at the back portion of the hollow object. These fasteners are placed through a slot from the front part of the hollow object. The second part of the fastener, being usually a bolt or a screw, supports the second object by forcing the legs of the fastener (as described for example in U.S. Pat. No. 4,500,238) to open or expand, thereby securing the two objects together. The fasteners of this type have greatly improved the prevailing torque (torque required to render a screw loose), as well as the pulling force (pulling force applied on a screw to the point of failure) of the system.
The fasteners of the type described in U.S. Pat. No. 4,500,238 have a funnel portion into which an expanding is driven for expanding the legs of the fastener. This funnel has a bucket-like shape which has been impressed on the legs during the manufacture of the fastener. This impression derived funnel is rather inflexible and in some occasions has a tendency to drive the expanding member in undesired direction.
An example of fasteners having oblong funnels is described in U.S. Pat. No. 6,280,129 B1 (Lowry et al.), which is incorporated herein by reference. U.S. Pat. No. 6,409,443 B1, which is also incorporated herein by reference, discloses a spring fastener having a Y-shaped cut funnel, and which may eliminate, if so desired, barbs which are used to support the fastener in one of the parts to be connected together by said fastener.
The fasteners of the type used in industrial applications, wherein the fastener is first inserted into the slot of a sheet, usually a metal sheet, such as the frame of an automobile for example, have barbs which secure initially the fastener on the sheet. After the fastener has been secured on the sheet, the fastener cannot be extracted from the slot without destruction of either the slot or the fastener, since the barbs are disposed against the lower surface of the sheet without the feasibility of springing back when the fastener is pulled from the region of the upper surface of said sheet.
A large number of advantages are derived from the critical configuration of the barbs of the present invention, which allow the extraction of the fastener without destruction of the slot and/or the fastener, as well as the retention of the fastener in slots of various widths preventing rattling noises, as described in detail hereinbelow.